Merge pull request #123 from Zac300/allocate-batchrequest-on-miss

Allocate batchRequest only on cache miss

Author: pavelnikolov

dataloader.go

@@ -227,10 +227,6 @@ func NewBatchedLoader[K comparable, V any](batchFn BatchFunc[K, V], opts ...Opti
 // the registered BatchFunc.
 func (l *Loader[K, V]) Load(originalContext context.Context, key K) Thunk[V] {
 	ctx, finish := l.tracer.TraceLoad(originalContext, key)
-	req := &batchRequest[K, V]{
-		key:  key,
-		done: make(chan struct{}),
-	}
 
 	// We need to lock both the batchLock and cacheLock because the batcher can
 	// reset the cache when either the batchCap or the wait time is reached.
@@ -254,6 +250,13 @@ func (l *Loader[K, V]) Load(originalContext context.Context, key K) Thunk[V] {
 		return v
 	}
 
+	// Only a cache miss needs a batch request: allocating it (and its channel)
+	// before the cache check above wastes an allocation on every cache hit.
+	req := &batchRequest[K, V]{
+		key:  key,
+		done: make(chan struct{}),
+	}
+
 	thunk := func() (V, error) {
 		<-req.done
 		result := req.result.Load()